Transcript

Robyn Williams: Why did we begin to count? Some animals do it as well.

Imagine some coins on a table, three or four of them. Most of us can tell instantly, well almost, how many there are. A few animals, like dogs can do this as well. What they've done At Bristol. (yes that's the name of the Science Centre - At Bristol) is to see how quick people are at this and who isn't able to do it at all. Penny Fidler is At Bristol, Brian Butterworth is from the University College, London.

Penny Fidler: The experiment was one of the largest maths experiments in the world and it was to find out about how people do maths so we've used our visitors, we wanted our visitors to become part of an enormous real life experiment.

Robyn Williams: And as they came in the door you bailed them up and asked them to do what?

Penny Fidler: We didn't exactly sort of drag them in, what we did was create a really appealing exhibit so they could actually feel like they were playing but at the same time take part in one of Professor Brian Butterworth's experiments.

Robyn Williams: Well Brian Butterworth has been on the Science Show many times, welcome back. Tell me, what did you do to them?

Brian Butterworth: Oh well, what we did is we had a touch screen experiment, in fact we had three experiments. In one of them you had to say whether the number of dots that you were looking at corresponded to a numerals, so there were 7 dots and 7 numerals you would touch the screen where it said yes. Another one you had to say which of two numbers was bigger, and the third one you had to say whether 5 plus 3 was 9 or not, again you touched the screen. And we took the reaction times from the subjects; so how long it took them to actually touch the screen from the time we displayed the stimulus so there was 18,000 x 33 reaction times collected and analysed so better calculators in your audience than I am can work that out, but it was a lot anyway. And what we were interested in was how people performed on these very basic numerical tasks so it wasn't meant to test how well you'd been educated, because what we were interested is basic numerical ability. And actually what we're talking about today at the British Association, is the results of just one of these experiments and a very stunning result indeed.

One of the things that's been known for 50 years is that if you ask people to name the number of dots in an array, how long it takes them to say the number depends on how many dots there are. But it's not a straight-line relationship between the number of dots and reaction time, it actually looks like two lines. It looks like one line for dots up to four and another line for dots five to ten. It's about 50 milliseconds per dot for 1 to 4, and about 250/300 milliseconds per dot for 5 to 10. And this has suggested to people that they were really two processes here, one for the small number of dots called subitising and one for a large number of dots called counting.

But there was a factor which affected the subitising range, particularly 1 dot to 3 dots, and that was gender and females were slightly but significantly faster than males.

Penny Fidler: The participation was absolutely amazing. We had 18,000 of our visitors have taken part in the largest maths experiment that the world has ever seen and from that we were able to look at very small effects across lots of people. So one of them, as Brian has just said, is that we've actually found that women are faster than men at this instant judgement type of counting. This is the type of counting where you see three coins on as table and you know it's three, you don't actually go 1, 2, 3, you know there's 3, when you get to five of these coins then you actually have to start counting, 4 or 5 you have to actually count them. So what Brian's found is that women are actually faster than men in this particular range, so we're very, very excited about that, we're very excited to be running such a huge experiment that can actually get our visitors contributing to scientific knowledge in Britain.

Robyn Williams: Brian, why are women faster than men? Is it because they're more used to picking up small change?

Brian Butterworth: (Laugh) Well, the honest answer is we don't know.

Robyn Williams: More work needs to be done?

Brian Butterworth: Certainly more work needs to be done, which of course will take more funding. But it is very interesting, because this ability to subitise, to recognise the number of things in an array without counting could be the basis of number sense and it's certainly been shown that being able to recognise small numerosities helps children learn to count, learn to add and learn to subtract. So, think of yourself as a 3 year old child counting objects in an array with words that you've had to learn specially for this purpose, the words one, two and three, and how do you know if you've done it right. Well, if you can subitise those three and you also count 1, 2, 3 you say: Oh yes, I must have got right, and so this helps you learn a really basic cultural skill which is counting. And if you haven't got this ability to subitise, it may be you're going to find it very difficult to learn numerical concepts and in fact, we have discovered a few people who don't seem to be able to recognise these small numerosities without counting and these people are actually very bad at maths, they're dyscalculic and dyscalculia seems to be something which affects maybe 5% of the population, so we're still trying to understand that. But an inability to subitise certainly goes with severe dyscalculia.

Robyn Williams: And if Brian Butterworth is right, they've now shown that about 5% of the population lacks this ability rather in the same way as some people are colour blind and it means they can't do maths like others and need special assistance. It could be a major discovery. Professor Brian Butterworth is from University College, London. Meanwhile, will they do more huge public experiments At Bristol? Penny Fidler.

Penny Fidler: Yes, we'd love to. We've actually set up recently some more experiments about handedness with people at Bristol University, we've set up some surveys about fertility issues, but also Brian and I have been discussing ways that we can work together in the future and more experiments we could do. We're very, very keen on bringing together the scientists with the public in this way and actually giving scientists and psychologists a humungous population that they can work with, with people from all the different backgrounds, all different ages and different genders.